Transfer prints enjoy a big popularity, as they allow the application of any graphic presentation, patterns, images or type faces, in particular on clothes like T-shirts, sweatshirts, shirts or also other textile substrates like for instance mouse-pads. Of particular interest are ink-jet transfer systems (ink-jet transfer prints), providing the potential users with the possibility of an individual selection of electronically processible and by means of graphic presentations which can be stored on a computer, and which can eventually be printed or ironed on, respectively, onto his desired garment or another textile substrate (support), respectively, by the user himself. Thereby, in a first step, the desired, electronically processible image is produced by the user of the transfer print by means of a computer, which is transmitted from the computer to a suitable printer, for example an ink-jet printer, which in turn prints the desired image onto the transfer system. The transfer print thus prepared has to display a structure which allows the further use for printing onto for example a textile substrate. By means of a suitable transfer print, the desired graphic presentation is brought to adhesion onto the desired textile substrate. Usually, graphic presentations are applied under supply of heat and pressure by a hot copy, and optionally by a prior cold copy onto the desired textile substrate.
In recent years, efforts have been undertaken in order to improve the hot transfer systems as well as to enable the printing of the desired graphic presentation onto the textile substrate with a satisfactory quality.
For instance, U.S. Pat. No. 5,242,739 describes a heat-sensitive transfer paper which is capable of receiving an image and comprises the following components: a) a flexible cellulose containing, unwoven, textile-like paper which has a superior and an inferior surface and b) a melting transfer-film layer which is capable of receiving an image, and which is situated onto the superior surface of the paper support, c) as well as optionally an intermediary hot-melt layer. The film layer is composed of about 15 to 80 weight-% of a film-forming binder and about 85 to about 20 weight-% of a powder like thermoplastic polymer, whereby the film-forming binder and the thermoplastic polymer have a melting point of between about 65° C. and 180° C.
U.S. Pat. No. 5,501,902 represents a further development of U.S. Pat. No. 5,242,739, which is composed of a two-layer system as well, whereby, however, for the improvement of the printing image, an ink viscosity agent is further contained. Furthermore, in the transfer print of U.S. Pat. No. 5,501,902, preferably a cationic, thermoplastic polymer is contained for the improvement of the ink-absorbing capacity.
As pigments for the receipt of the ink dyestuff, in the prior art, usually polyesters, polyethylene wax, ethylene-vinylacetate copolymers, and as a binder, polyacrylates, styrene-vinylacetate copolymers, nitrile rubber, polyvinylchloride, polyvinylacetate, ethylene acrylate copolymers and melamine resins are mentioned.
In WO 98/30749 (Océ-Switzerland) an ink-jet transfer system is described, which comprises a carrier material, a hot-melt layer being applied onto the carrier material and at least an ink-receiving layer. Thereby, the ink-receiving layer is a mixture of a highly porous pigment and a binder, whereby the molecules of the pigment and optionally of the binder as well as optionally of the hot-melt are capable of forming chemical bonds with the dyestuff molecules of the ink.
A special difficulty, however, is associated with transfer prints, which shall be applied onto a dark textile support. Since the dyestuffs are transparent against dark backgrounds, i.e. maximally perceptible as shadow, first of all a light contrast background has to be created to make the desired colored image better visible. According to the prior art, for this, in the course of a 2-step method or a one-step method, a transfer print is applied onto a dark piece of textile. In case of the conventional 2-step method, a white textile fabric equipped with a hot-melt adhesive on the back is laminated with a transfer foil that was imprinted by a xerographic method (or ink-jet) and then pressed with the hot-melt adhesive side on the dark garment to be imprinted (T-shirt) by means of a transfer press at ca. 180° C. and a pressure of about 7 bar. The image side with the thin foil (transfer layer) on it thereby is protected by a silicone paper. After the transfer operation that lasts about 10 seconds, the silicone paper is removed. The adhesion of the transfer print system on the dark garment is achieved by means of a polyethylene or polyester/polyamide textile adhesion (i.e. a hot-melt adhesive) of the contrast support on the textile substrate.
The whole system is felt to be unpractical by the user in so far as one needs a laminator and/or a textile transfer press for the realization of the method, whereby in particular the washproofness or the adhesion of the white contrast support on the dark piece of textile, respectively, still is particularly unsatisfactory and in addition is appreciably impaired with each washing.
The known systems that are usable by means of a one-step method are based on a white, thick transfer foil with a thickness of about 400 to 600 μm which can be imprinted by an ink-jet method or a xerographic method and subsequently transferred on a dark piece of textile by means of a transferred press. The disadvantages of this system are in particular the unsatisfactory image quality immediately after the transfer on the piece of textile. The images look faint and blurred. Furthermore, the whole system is comparatively thick, makes an unaesthetic impression (armor-like) and it is not breathable. An additional major disadvantage is the fact that the user who does not have available a transfer press and consequently switches to the use of a commercially available iron is confronted with a sustainably impaired adhesion of the transfer foil on the piece of textile. This loss of adhesion is further accelerated by repeated washings.
A further disadvantage of both conventional print systems is their application process on the textile substrate, whereby the application of a contrast background on the piece of textile under markedly high pressure cannot be performed by private persons without adequate equipment. The pressures of at least about 7 bar (=7×105 Pa) often required for this can only be generated by a cost-intensive transfer press, whereby the users are mainly interested in a simple ironing on by means of a commercially available iron. The above mentioned disadvantages did significantly lead to the consequence that the currently sold transfer print systems did not become widely distributed in the market as desired, or were not very successful, respectively. On the contrary there still exists a great need for satisfactory systems that do not have the above-mentioned disadvantages.